Refractive Outcomes Of Sequential Intrastromal Corneal Ring Segments And Phakic Intraocular Lens Implantation For Keratoconus Management - 5-Year Follow-Up Study

Keratoconus is an asymmetrical and progressive corneal ectasia characterized by irregular astigmatism, myopia, and higher-order aberrations, causing loss of visual acuity. Intrastromal corneal ring segments (ICRS) implantation is an effective method for reducing astigmatism and higher-order aberrations. Although ICRS implantation significantly improves the ectasia, many patients with keratoconus have moderate to high myopia that require use of contact lenses or spectacles to correct the residual refractive error. The purpose of the study was to evaluate the short and mid-term efficacy, safety, and predictability of sequential implantation of ICRS and a phakic intraocular lens (pIOL) for therapeutic and refractive correction of keratoconus.

Department of Ophthalmology, Hospital de Braga, Braga, Portugal

Retrospective study, including patients with keratoconus who had Ferrara-type ICRS implantation with subsequent pIOL implantation after six to twelve months, for correction of ametropia, associated with corneal incision in the steepest topographic axis.  At 1- and 5-year follow-up after pIOL implantation, the main outcome measures were uncorrected and corrected distance visual acuity (UDVA and CDVA, LogMAR scale), manifest spherical equivalent in diopters (D), topography indices and central endothelial cell density. Efficacy and safety indexes were calculated at 1 and 5 years of follow-up.

The study included 28 eyes (24 patients) with a mean age of 28.3 years at the time of ICRS implantation; 7 iris-claw foldable lenses and 21 posterior chamber pIOL’s were implanted. Mean UDVA was 0.92±0.14 preoperatively, 0.71±0.13 six months after ICRS implantation (p=0.457), and 0.26±0.25 six months after pIOL implantation (p<0.001). Mean CDVA was 0.39±0.27, 0.25±0.24 (p=0.097), and 0.17±0.24 (p<0.001), respectively. Efficacy and safety index were equal or higher than 1.0, one year after pIOL implantation. Refractive astigmatism decreased after one (p=0.005) and five years (p=0.016) of ICRS implantation; SE decreased at 12 months after pIOL implantation (p<0.001), remaining stable at 5 years (p=1.000). 

Sequential ICRS and pIOL implantation provided good visual and refractive outcomes, indicating that it is a predictable procedure for refractive correction of keratoconus. The results demonstrated to be stable over a five-year follow-up period.